Method of and apparatus for burning of refuse



United States Patent [72] Inventors I Hermann Appelhans 11-2 Frankfurter Strasse 35, Kassel; Wolfgang Schumann, 351 Werdenstieg 22b, Hannover-Muenden, Germany [21] Appl. No. 787,981 [22] Filed Dec. 30, 1968 [45] Patented Dec. 1, 1970 [54] METHOD OF AND APPARATUS FOR BURNING F REFUSE 14 Claims, 6 Drawing Figs.

[52] U.S.Cl..... 110/13, 110/15, 110/36 [51] Int. Cl F23g /02 [50] Field ofSearch 110/8,12, 13, 36,

[56] References Cited UNlT ED STATES PATENTS 2,187,201 1/1940 l-lartleyetal. 110/12 2,948,237 8/1960 Toepel 110/36X 3,309,787 3/1967 Forsyth et al. 110/36X Primary Examinerl(enneth W. Sprague Attorney-Ernest G. Montague ABSTRACT: A method and apparatus for burning refuse, comprising guiding refuse in a circular path successively through a drying zone, a burning zone and a cooling zone, subecting the refuse during the continuous guidance to combustion air, and lifting and airing the refuse during the burning step. The apparatus includes an oven having an annular tunnel and including an annular grate turnable in the tunnel and having openings, a feeding station, a drying chamber, a burning chamber, a cooling chamber, and a discharge station in series in the tunnel in the direction of rotation of the grate, and means for feeding combustion air from the bottom of the annular grate. In the center of the oven is an afterbumer chamber having a waste gas opening for communication with the burning chamber, and a dust removing device is operatively connectable with the afterburner chamber.

Patented Dec. 1, 19 70 3,543,702

Sheet 2 014 \NVENTORS mdnn A elhans Wolfqanq Schumann BY Ernest, G.N\ONTAGUE ATTOR N Y Patentd I Dec. 1, 1970 Sheet 3 014 Fig.3

'NVENTORS mann Appe l hang E uv m6 a M m C 5 G M E V 6 A ORNEY The present invention relates to a method of and apparatus for burning of refuse. The technique of burning of refuse has been very extensively developed recently. A series of most different burning systems is known, in arrangements are applied which are equipped witha stepped up tipping grate, an advancing grate, a return slide grate, a stepped-up moving grate or a roller grate. Drum furnaces have also been know, which have a relatively great length in relation to their diameter, and in which the refuse moves through the drum. All these known burning devices are commonly characterized by the feature, that the refuse is conveyed at a predetermined angle from above to below during the burning. The refuse is subjected thereby to burning and is transformed into ashes and slag, which is removed either in solid or in liquid form.

It is also known that bunkers or storage devices for reception of the refuse corresponding to the portioning and dosing apparatus, magnet devices countercurrent of steel parts and crushing devices, as mills or the like are preset to these buming devices. Often, a vessel arrangement for production of steam follows the refuse burning arrangement already in operation. There, in particular, in large arrangements, the heat originating from the burning of the refuse is made useful by corresponding heat exchangers.

In all these known burning methods, the refuse is forcibly turned, in order to warrant a sufficient oxygen feed for the furthering of the burning process. The refuse is in a continuous movement during the burning process, which often turns out to be a drawback. This permanent movement causes namely, that intensive burning processes are torn apart and are choked. The refuse parts must be ignited later again, in order to continue the further burning. Furthermore, it has been shown as a drawback that this intensive refuse movement causes relatively large dust quantities, which must be fed out from the burning arrangement and must be precipitated in a dust removing device. These large dust quantities require a more often cleaning andoverhauling of the dust removing device.

It is, therefore, one object of the present invention to provide a method of and apparatus for burning of refuse, wherein it is assured, that intensive burning processes are not unfavorably interrupted. The refuse is moved and aired thereby only according to plan. Furthermore, the arrangement should be made such, that the refuse is guided a second time or several times through the burning zone, without requiring a renewed original feeding of the partly burned refuse at the input of the device. Furthermore, it is necessary, that the device requires relatively small space, in order to be able to be put into operation in small units. This object presents itself preferably in the burning of industrial refuse.

It is another object of the present invention to provide a method of and an apparatus for burning of refuse, wherein the refuse is fed during its circulation in a circular path successively through a dry zone, a burning zone and a cooling zone, and thereby is subjected to continuous feed of burning or combustion air. With particular advantage, the refuse is additionally lifted and aired during the burning phase. This takes place preferably at the end of the burning zone. In accordance with the present invention, the refuse can be fed under circumstances several times without renewed feeding through the burning zone.

The apparatus for performing the method is equipped with a furnace having a grate, which furnace is equipped with openings for inserting the refuse and for removal of ashes and slag, as well as equipped with support burners. The apparatus is characterized in that the furnace has an annular tunnel, in which an annular grate rotates. In the tunnel are thereby provided in the direction of rotation of the grate successively a feeding station, a drying station, a burning and cooling zone, as well as a discharge station and a combustion air feed is arranged below the annular grate. The annular oven has in its center an afterb'urning chamber, which is connected with the combustion chamber by meansof a waste gas opening, whereby a dust removing device and under circumstances heat exchangers are connectable with the afterburning chamber. It is, as a matter of course, also possible to provide the afterburning chamber outside of the annular oven.

Preferably at the end of the combustion zone, one or a plurality of lifting devices for lifting and airing the burning refuse are provided. The lifting device comprises a carrier equipped with prongs, which carrier projects through the oven wall into the combustion chamber and is rollable radially above the combustion plane and above the annular grate, respectively, into the refuse path. The carrier is thereby preferably equipped with pneumatically of hydraulically operating lifting cylinders.

In accordance with the present invention, a stripping device for the removal of ashes and slag from the annular grate is provided in front of the feeding station within the range of the annular grate. A height-adjustable slag breaker follows the stripping device, which slag breaker cleans continuously the grate. In a particular embodiment, the stripping device formed of a conveyor screw, which is mounted for height adjustment. Between the stripping device and the feeding station, a height adjustable separating wall is provided, which separates the cooling zone from the feeding zone. With particular advantage, the annular grate is movable in both rotary directions and controllable as to its speed continuously. The grate is composed of individual conical rings, whereby the rings are formed of segments. The individual rings of the grate have a relative distance, whereby the sum of the faces corresponds with the passage face for the combustion air. The annular grate is equipped with a roller bearing and has water closures which are disposed on both sides.

By the method of the present invention and the apparatus brought into operation, different advantages are brought about in comparison with known refuse burning processes. The transportation of the refuse is performed by means of an endless conveyor member, which collects during its movement the refuse. By this circular path, it is possible in a simple manner, to subject the refuse which is partly not completely burned out, to a renewed circulation. A particular refuse parts feeding as it is necessary in' the known devices, is here eliminated. It is merely required, to lift the separating wall for a predetermined amount. Thereby, of course, the stripping device is also lifted. This method step can also be performed partly, so that the above stated already well-burned refuse parts are removed as slag, while lower disposed not yet burned up refuse parts are subjected to a renewed burning process. By the continuous control of the speed of the annular grate and by the possibility of the reversal of the direction of rotation, respectively, badly burned up refuse parts can remain longer in some zones during one circulation and can be returned into such zones, respectively. By this arrangement often an additional total circulation of the refuse is avoided in the device. Furthermore, by the method of the present invention, the continuous burning process is not disturbed. The accumulating dust quantities in the waste gases are thereby relatively low.

The device for lifting and lowering the refuse, designed in accordance with the present invention, lifts the refuse carefully in order to air it and in order to feed oxygen thereto. The refuse falls back thereby in the lifted position of the carrier equipped with prongs in portions to the annular grate. In this manner, the refuse comes into engagement once or several times with the carrier of the prongs, is lifted and aired and then again lowered into the burning plane. This lifting movement is likewise controllable in its speed. Thereby, the possibility is given to feed an exactly dosed quantity of oxygen necessary for its combustion.

The arrangement of the annular grate and of the supporting burners, as well as of the waste gases emergence, makes possible the countercurrent process, in which the hot waste gases strike over the fed refuse and dry the latter thereby.

Contrary to the conventional refuse burning devices, the apparatus in accordance with the present invention can be put into a comparatively small space. In the conventional arrangements, it is necessary to provide a predetermined grate face for a predetermined output. Depending upon the type of structure, for instance a grate of a length of 8m. and of a width of 1.2m. corresponds thus to a length of the body of the furnace of at least m. The same grate face size requires, in case of use of an annular grate only an outer diameter of 4.5m.

The method according to the present invention permits the combination of different method steps. In a similar manner, it is also possible to vary constructively the arrangement without abandoning the concept of the present invention.

With these and other objects in view, which will become apparent in the following detailed description, the present invention, which is shown by example only, will be clearly understood in connection with the accompanying drawings, in which:

FIG. 1 is a section along the lines Il of FIG. 2;

FIG. 2 is a top plan view of the device, partly in section along the lines ll-Il of FIG. 1, a portion being broken away for the purpose of better demonstration;

FIG. 3 is a fragmentary elevation partly in section along the lines Ill-ill of FIG. 2;

FIG. 4 is a section of the annular grate and of the stripping device;

FIG. 5 is a section along the lines V\/ of FIG. 2 of the lifting device; and

H6. 6 is a top device.

The refuse burning apparatus, designed in accordance with the present invention, does not convey and burn the refuse in an upwardly directed movement, rather in the horizontal. The refuse rests thereby on an annular grate l, which is surrounded by a tunnel 2 forming an oven having a roof 3. The roof 3 has different heights, which are alined according to the different zones of the refuse treatment. A feeding station 4 is provided (P16. 2), in which the refuse is fed by means of chute or the like. The feeding of the refuse can be dosed in known manner and can be pretreated. A drying zone follows the feeding station 4 on the annular grate l and in the oven, respectively, in which drying zone the refuse is freed from the water brought into the latter. In the tunnel 2 and in the oven wall, respectively, one or a plurality of supporting burners 5 are arranged, which ignite the refuse and which indicate the start of the combustion zone. The supporting burner or supporting burners 5 are switched off upon reaching the combustion temperature, that means in a phase of the initial ignition. The hot smoke gases brought in from the supporting burner strike over the refuse additionally in the drying zone in a counter current procedure. A waste gas opening 6 is provided, which leads into an afterburning chamber 7. The afterburning chamber 7 is provided inside of the furnace with particular advantage. It is, however, also possible to arrange on the outside the afterbuming chamber 7.

The combustion oven is divided into a drying zone, a combustion zone and a cooling zone, the latter being passed by the annular grate I. At the end of the cooling zone, a stripping device 3 is provided, with which the refuse, transformed now into ashes and slag, is removed from the annular grate l. The ashes and slag, respectively, enter the ashes channel 9. A separating wall it) follows the stripping device 8. The stripping device 3 and the separating wall it) are adjustable as to their height. Different control openings 11, distributed along the periphery of the device, permit at any time the observation and the interference, respectively, with the burning and transformation process. Preferably at the end of the combustion zone is provided alifting device 112, which has a carrier M equipped with prongs. The oven wall carries at this point openings 13, through which the prongs project into the combustion chamber. The openings 13 are formed as long borelike slots, which permit a lifting movement of the refuse in vertical direction to the annular grate 1.

The annular grate l is composed of individual rings 15 which leave free therebetween grate crevices 16. The rings 15 plan view partly in section of the lifting can be formed of segments. As is shown in MG. 3, behind the stripping device h a slagbreaker 117 is inserted, which enters into the grate crevice 16 of the annular grate i and cleans the latter, in order that after renewed refuse feeding the feed of the lower air is not prevented.

The ash and slag particles falling through the ring grate during the burning process and during the circulation, respectively, extend into an ash removal device 18. in order to feed the necessary combustion air, a low wind channel 19 is provided. This low wind channel is connected with the ash removal device 18, so that the lower wind is fed in a countercurrent procedure through the ash removal device to the refuse to be burned. The ash removal device 18 has a lower part 27, in the range of which a water circulation cleaner 2.) is provided. The ash and slag particles float away with the water. Additional cleaning openings 28 permit at any time the control and the interference, respectively, in the ash removal device 18.

The annular grate i. has a bottom structure 20, which is formed preferably of a profile steel framing. The annular grate 1 has a roller bearing 21, whereby preferably the rollers are immovably arranged. Right and left on the outside of the annular grate 1 water closures 22 are provided, into which suspension ledges 23 of the annular grate l penetrate and, thus, create a pressure-tight connection. The water of the water closures 22 can be released into a groove 24. Slag and ash particles, which have fallen down from the annular grate it during the combustion, are thus brought outwardly from the water closures 22 and removed.

In the afterburner chamber 7, a burner 25 is provided, which is preferably formed as a bottom burner. A protector is arranged thereabove, which protects the burner from falling down flying particles.

In the refuse burning device according to the present invention, the refuse is transformed in a horizontal plane into ashes and slag. The annular. grate 1 is formed continuously and in its rotary speed endlessly'controllable, At the feeding station the refuse to be burned is fed. It travels through a drying zone and reaches thereafter into a combustion zone in which it is ignited by the supporting burners 5. The heat created during the combustion moves slowly on the annular grate i and pulls on the other hand against the refuse newly fed thereto. The refuse is covered by the hot smoke gases and predried. The smoke gas pulls through the waste gas opening 6 into the after-burner chamber 7. From here, the waste gases leave the afterburner chamber 7, to which, under circumstances, a dust removing device and finally also a heat exchange device is connected.

. Particularly in case of larger devices it is of advantage to make use of the combustionheat. This can be realized by connecting thereto a power station. When the refuse is burned out and has been transformed into ashes, it is then moved from the annular grate 1 by the discharge device 8, which consists, for instance, of a conveyor screw of heat resistant material, and transported into the ash channel 9. From here, the ashes are further transported mechanically or hydraulically. The actual combustion chamber and the oven, respectively, is divided between the feeding station 4 and the removing device ii by a separating wall 10. This separating wall N9 is preferably movable and can, if required, be lifted to a higher level. Likewise, the possibility exit exists to lift upwardly the heat resistant conveyor screw. Thereby, the possibility is created that not completely burned out refuse can move again through the entire combustion chamber. This procedure is under circum stances repeated several times, until the refuse is completely burned out.

The annular grate 1 is rotatable in both directions. By this arrangement, it is brought about, that certain waste material difficult to be burnt can be retained for a longer time period in the combustion zone and that these materials can be fed several times through certain zones, respectively.

During the combustion process, the refuse rests on the annular grate and can burn undisturbed. In order to guarantee a sufficient oxygen feed, the refuse is lifted and again lowered in portions by means of one or a plurality of lifting devices 12, which can be arranged outside or inside of the oven ring. The lifting process extends thereby in its width, preferably to about 30-50 cm. The lifting device 12 shown in FIGS. 2, 5 and 6 for lifting of the refuse is rollable in forward and rearward direction and permits simultaneously the lifting and lowering of the refuse by means of the prongs, which jointly form the carrier 14. The prongs are arranged at a predetermined distance from each other. While the annular grate 1 moves slowly and transports the refuse, the lifting device 12 rolls with its carrier 14 into the combustion space. By this arrangement, the prongs slide at a low height or a low level above the annular grate l and enter in the refuse path. The prongs of the carrier 14 are of high heat resistant material and slimly pointed. By such arrangement, it can be brought about that cans and other metal parts found in the refuse are pierced through and are not piled up. When the carrier 14 reaches its end position, it is lifted by the lifting device 12. The lifting process extends over a height of about 20-60 cm. By this arrangement, the refuse is lifted and aired. The oxygen and the hot burning gases can approach the refuse all over. When the lifting process is terminated, the carrier is rolled back into its original position, that means it is withdrawn through the oven wall. The refuse supported by the prongs and also cans and other metal parts are stripped off on the oven wall. The upper edges of the openings 13 in the oven wall, which extend perpendicularly like a long hole, have for this purpose a layer of a special alloy. The lifting device 12 works over a predetermined time interval, which is adjustable, so that each refuse charge, which is on the annular grate ll, is lifted by the lifting device 12 under circumstances several times or lifted in overlapping cycles and is also aired.

Behind the lifting device 12, the cooling zone is provided in which the burning out, that means the complete transformation of the burning refuse into ashes and slag takes place.

While we have disclosed one embodiment of the present in vention, it is to be understood that this embodiment is given by example only and not in a limiting sense.

We claim:

1. A method of burning of refuse, comprising the steps of guiding refuse in a circular path successively through a drying zone, a burning zone and a cooling zone, subjecting said refuse during the continuous guidance to combustion air, and lifting and airing said refuse during said burning step.

2. The method, as set forth in claim 1, which includes the step of repeated guidance of said refuse through said burning zone without renewed original feeding.

3. An apparatus for burning of refuse comprising:

an oven including a grate having openings for feeding refuse into said oven and for removal of ashes and slag;

said oven having an annular tunnel;

said grate being of annular shape for turning in said tunnel;

a feeding station, a drying chamber, a burning chamber, a

cooling chamber, as well as a discharge station disposed in series in said tunnel-in the direction of rotation of said grate;

means for feeding combustion air from the bottom of said annular grate,

said oven is of annular shape and includes inits center an afterburner chamber,

said afterburner chamber has a waste gas opening for communication with said burning chamber, and a dust removing device operatively connectable with said afterburner chamber.

4. The apparatus, as set forth in claim 3, which includes a heat exchanger operatively connectable with said afterbumer chamber.

5. An apparatus for burning of refuse comprising:

an oven including a grate having openings for feeding refuse into said oven and for removal of ashes and slag;

said oven having an annular tunnel;

said grate being of annular shape for turning in said tunnel;

a feeding station, a drying chamber, a burning chamber. a cooling chamber, as well as a discharge station disposed in series in said tunnel inthe direction of rotation of said grate;

means for feeding combustion air from the bottom of said annular grate; and

at least one lifting device disposed at one end of said burning chamber and adapted for lifting and airing the burning refuse.

6. The apparatus, as set forth in claim 5 wherein:

said lifting device comprises a carrier having prongs;

said carrier projecting through a wall of said oven into said burning chamber;

means for rolling said carrier radially above the burning plane and above said annular grate, respectively, into the path of the refuse; and

pressure cylinders for lifting and lowering said carrier.

'7. An apparatus for burning of refuse comprising:

an oven including a grate having openings for feeding refuse into said oven and for removal of ashes and slag;

said oven having an annular tunnel,

said grate being of annular shape for turning in said tunnel;

a feeding station, a drying chamber, a burning chamber, a cooling chamber, as well as a discharge station disposed in series in said tunnel in the direction of rotation of said grate;

means for feeding combustion air from the bottom of said annular grate; and i a stripping device in front of said feeding station within the range of said annular grate for the removal of slags from said annular grate.

8. The apparatus, as set forth in claim 7, which includes, a height adjustable slag breaker operatively connected with said stripping device for continuous cleaning of said grate.

9. The apparatus, as set forth in claim 7, wherein:

said stripping device comprises a conveyor screw, and

which includes;

means for mounting said conveyor screw adjustable to its height.

10. The apparatus, as set forth in claim 7, which includes, a separation wall adjustable as to its height and disposed between said stripping device and said feeding station, in order to separate said cooling chamber from said feeding station.

11. An apparatus for burning of refuse comprising:

an oven including a grate having openings for feeding refuse into said oven and for removal of ashes and slag;

said oven having an annular tunnel;

said grate being of annular shape for turning in said tunnel;

a feeding station, a drying chamber, a burning chamber, a cooling chamber, as well as a discharge station disposed in series in said tunnel in the direction of rotation of said grate,

means for feeding combustion air from the bottom of said annular grate;

means for rotating said annular grate in two rotary directions; and

means for endless control of the rotary speed of said grate.

12. The apparatus, as set forth in claim 11 wherein:

said grate comprises individual conical rings; and

said rings are formed of segments.

13. The apparatus, as set forth in claim 12, wherein said individual rings of said grate have a relative distance, so that the sum of the free face corresponds with the passing face for the combustion air.

14. An apparatus for burning of refuse comprising:

an oven including a grate having openings for feeding refuse into said oven and for removal of ashes and slag;

said oven having an annular tunnel;

said grate being of annular shape for turning in said tunnel;

a feeding station, a drying chamber, a burning chamber, a cooling chamber, as well as a discharge station disposed in series in said tunnel in the direction of rotation of said grate;

water closures disposed on opposite sides of said annular grate. 

